As summarised… Once, at Śrāvastī, the bhikṣuṇī (Buddhist nun) Sthūlanandā encountered an orphaned girl on her alms round. Realising she was without any support, she encouraged and guided her to be a nun. Later, due to being enmeshed with afflictions, the girl returned to the lay life. Sthūlanandā again encountered her later, and asked how she was surviving. The girl replied that as she is without any support, she is living with much hardship. Sthūlanandā asked her to consider being a nun again, which she again did, through her.

长者婆罗门见已皆共讥嫌。诸释迦女能为善事。或时出家而修梵行。或时罢道还染俗尘。随情所为岂非善事。诸尼闻已白诸苾刍。苾刍白佛。

When elder Brahmins saw this, they together ridiculed her, saying how the Buddha’s nuns might sometimes renounce to practise the pure practices, or sometimes return to the defiled lay life, if they feel like doing so. When all the nuns heard this, they told this to the monks, who told this to the Buddha.

The Buddha thus decided that as nuns who return to the lay life have such misgivings, from then onwards, all nuns who returned to the lay life are not able to again renounce to be nuns. This is to prevent others from sneering at, to damage the (reputation of) Buddha’s Dharma teachings. As such, once nuns give up their (monastic) Dharma robes, having already returned to the lay life, they should not again be enabled to renounce to be nuns. If with those who re-renounce, the teacher (or ordination master) attains transgression from breaching the Dharma (as he or she should now be aware of the above rule that disqualifies reordination of nuns and reordained nuns).

Question: Why did the Buddha forbid repeated ordination of women?

Answer:All precepts and rules were set by the Buddha for facilitating spiritual cultivation, to help all to avoid evil, do good and purify the mind. Precepts for monastics were created by the Buddha when specific incidents occurred, as recorded in the Vinaya, that exemplify why each precept or rule is needed. As expressed by the incident above, the Buddha knew that females are generally more easily emotionally attached to their afflictions and worldly life.

As such, other than to not let others ridicule the Triple Gem (of the Buddha, Dharma and Saṅgha) for repeated ordination of the same ones who returned to the lay life, he set the rule allowing only one-time ordination for females, to ensure that their determination to be fully committed to the monastic life is firm. This rule was made out of compassion, to uphold the respectable reputation of the Triple Gem stably to best benefit all, and to facilitate all females’ clear commitment.